Apparatus for flame spraying surfaces of varying diameters



June 15, 1965 A. J. THOMA ETAL APPARATUS FOR FLAME SPRAYING SURFACES OF VARYING DIAMETERS 2 Sheets-Sheet 1 Filed Aug. 16. 19.60

INVENTORS ALBERT J. THOMA CORNELIUS J. BOGERT JR I WILLIAM F. BROWN M, My

ATTOREQYS FIG. 2

June 15, 1965 A. .1. TH OMA ETAL 3,139,001

APPARATUS FOR FLAME SPRAYINQ SURFACES OF VARYING DIAMETERS Filed Aug. 16, 1960 2 Sheets-Sheet 2 m WORK r-'- 8 REM.

5 LEAD MIN.

BASE LINE FIG. 4

INVENTORS ALBERT J. THOMA I WYGORNELIUS J. BOGERT JR WILLIAM F. BROWN United States Patent APPARATUS FOR FLAME SPRAYING SURFACES 0F VARYING DIAMETERS Albert J. Thoma, Mountain View,'Coruelins .I. Bogert, Ira, Fair Lawn, and William F. Brown, Butler, N.J., assignors to Thiolrol Chemical Corporation, Bristol,

Pa., a corporation of Delaware Filed Aug. 16, 1960, Ser. No. 49,904 6 tl'laims. (Cl. 118-318) The present invention relates to an improved apparatus for uniformly coating surfaces and more particularly to coating surfaces with a flame spray of molten solids, such as refractory and erosion resistant materials and metals.

While the apparatus of the present invention may have other applications, it is particularly effective for coating the inside surfaces of hollow rocket motor casings. Such casings may be constructed of a thin gauge metal, or as a composite section of connected tubes, and have cylindrical, spherical, conical or other curved sections concentric about an axis of revolution. A refractory coating is desirable between the metal casing and fuel in rocket engines to at least partially insulate the metal casing from the high temperature of the burning fuel and to resist the erosion produced by the flow of gases at high velocity. A number of different refractory materials have been used to coat the interior of rocket engine casings, but one material which has been found to be especially effective for this purpose is a metal oxide described and claimed in U.S. Letters Patent 2,707,691, issued to William M. Wheildon on May 3, 1955. This material is supplied in solid form and must be melted and atomized to apply it in a uniform layer. To this end, a rod of the material may be subjected to a torch flame which melts and atomizes the material to form molten particles and the particles are projected by the blast of the flame onto the surface to be coated where the molten particles solidify. Also, in some rocket engines it is necessary to apply a thin coating of metal to the rocket engine casing to provide a suitable bonding surface for the refractory material.

One of the objects of the present invention is to provide an apparatus for applying a molten atomized coating uniformly on a surface of varying radial distance about an axis of revolution.

Another object is to provide an apparatus for relatively moving a flame spraying nozzle and surface to be coated so as to cause the nozzle to follow the irregular contour of the surface at the same distance therefrom.

Another object is to provide an apparatus for applying a flame spray coating on a curved surface in a helical path at a constant linear rate and pitch.

Another object is to provide an apparatus of the type indicated for flame spraying a uniform coating on the inside surface of a rocket motor casing.

Still another object is to provide an apparatus of the I type indicated which is of relatively smple and compact construction, economical to manufacture and one which is reliable in operations These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings:

FIGURE 1 is a perspective view of an apparatus incorporating the novel features of the present invention which adapt it to uniformly coat a surface having varying radial dimensions about an axis of rotation;

FIGURE 2 is a diagrammatic view of a control mecha- "ice nism which illustrates the principle of varying the speed of rotation of the workpiece and rate of lead of the nozzle in proportion to changes in the radius of the surface to apply the coating at a constant rate in a helical path of uniform pitch;

FIGURE 3 is a perspective View of the unit for feeding the solid coating material and a combustible mixture to the flame spray nozzle;

FIGURE 4 is a diagram illustrating the variation in the rotative speed of the workpiece and lead of the nozzle proportional to the radius of the surface to maintain a helical spray pattern of constant pitch;

FIGURE 5 is a perspective view of the controls used in a commercial embodiment of the invention;

FIGURE 6 is a perspective view showing an indicating mechanism for resetting the nozzle to a precise position where a coating operation has been stopped; and

FIGURE 7 is an end elevational view showing the flame spray nozzle for applying a coating to the surface of a regeneratively cooled type of rocket engine.

Referring now to the drawings, FIGURES 1 and 2 illustrate an apparatus incorporating the present invention, but showing a simplified drive and control mechanism to illustrate the principle of the invention. The apparatus operates automatically to compensate for variations in the radius of the surface from its axis of rotation to maintain the flame spray nozzle at the same distance from the surface, a constant relative speed between the surface and nozzle, and relatively move the nozzle and surface to produce a helical spraypattern on the surface of constant pitch.

As illustrated in FIGURE 1, the apparatus 10 is generally similar to a lathe and has split bearings 11 and 12 arranged in spaced relation for supporting a workpiece 13, such as a rocket engine casing, for rotation about a fixed axis. As shown in FIGURE 1, the workpiece has a cylindrical section 13a and a conical section 13b at the end of the cylindrical section and forming the converging portion of a nozzle. The apparatus is particularly adapted to coat the inside surface of the workpiece 13 which may comprise a thin section of aluminum, stainless steel or other suitable material. 1 It will be understood, however, that the surface of the rocket engine casing or other part to be coated may have other curved forms, either converging or diverging, which are concentric to a central axis about which the workpiece rotates. The workpiece 13 may be driven by any suitable variable speed drive for varying its rotative speed in proportion to variation in its radius to maintain a constant peripheral speed of the surface to be coated. In the embodiment illustrated in FIG- URE 1, the variable speed driving means for the Workpiece 13 comprises a driven element 14 mounted fast thereon and a driving element 15.

A flame spray nozzle 18 is mounted on the apparatus for movement longitudinally of the workpiece 13 to coat its inner or outer surface. While the apparatus of the present invention may be used to apply other coatings, such as metals, it is particularly adapted for applying a ceramic, erosion resistant coating which is melted and atomized by a flame and propelled by the flame in a di verging pattern. The flame spray nozzle 18 is located at one end of a long tube 19 having a mixing chamber 20 for combustible gases at its opposite end. Supply lines 22 and 23 are connected to the mixing chamber 20, see FIGURES 1 and 3, for supplying a combustible mixture, such as oxygen and acetylene or natural or manufactured gas. Nozzle 18 comprises an orifice from which the combustible gases escape and burn to propagate a diverging flame. The tube 19 extends from the mixing chamber 20 which, in turn, is attached to a casing 24 having a mechanism for feeding the coating material 21. The feeding means comprises feed rolls 26 and 27 at the rear of ,rial therebetween and an electric motor the mixing chamber for feeding the rod of coating mategearing for driving the feed rolls.

' The assembly of casing 24, mixingchamber 20'an'd I tube 19 are supported on a rod 28 depending from and slidable through a horizontally movable'carriage 29; The

depending rod 28 extends through a sleeve 30 on the casing 24 and the rod and sleeve have a screw threaded'engage'ment for initiallyadjusting the position ofthe tube 19 relative to the carriage'29. Thus, the" flame spray nozzle 18 is supported at the end of tube 19 in spaced relation to the surface to be coated, is movable with the carriage 29 longitudinally ofthe hollow casing and is ,mova-' 25 and reduction splined shaft 51 to permitrelative longitudinal movement. The splined shaft 51, in turn, meshes with a horizontally arranged rack 52 mounted to slide in spaced bearing guides 53. Horizontal rack 52 has a yoke 54 straddling a friction driving disc 55 mounted to slide on a splined shaft 56 driven by a constant speed'electric'motor 57 through reduction gearing. The periphery of the friction disc. 55 en- 1 gages the face, of the driving element 15 and rotates the ble vertically relative to the'carriage to adapt; the nozzle I ,to be'maintained at a fixed distancefrom the. surface,-

Carriage 29 is mounted to slide on a horizontally extending rod 34 mounted on brackets 35 projecting from a frame member on the apparatus 10. The carriage 29 comprises spaced bearing blocks 36 and 37 positioned between plates 38 and '39 and having a vertically arranged bearing 40 for slidably mountingthe depending'rod 28. Carriage 29 is slid along the fixed. rod 34 longitudinally of the apparatus ltiby a hydraulic ram .41 having a cylinder .42 and piston rod'43 connected to the carriage... As the carriage 29 moves along the apparatus 10, the frame spray nozzle 18 at the end of tube 19 moves longitudinally I of the surface of the workpiece to :be coated. The flame spray nozzle 18 is moved radially'with spect to the surface to be coated by means of a camfollower45 on the upper end of'rod 28 which engages'a contour cam 46. The cam followerf 45 islin' the form of a plate having a collar attached to-the upper end of the I ea- 1 latter at a speed which varies in accordance with the radial position of" the disc .55 from the axis of rotation of the disc. As the radial movement of the driving disc 55 exactly follows changes inthe/radius of the work-piece 13 through the contour cam ,46, camfollower 45 and racks 5t); and- 52 the peripheral speed of thesurface being coated 'is maintained constant. 'For example, the constant speed driving disc SS may be positioned at the same radial distance from the axis of rotation of the dis'c;15 as the surface V being coated is from its axis of rotation so as to maintain of the pump forooperating the ram in opposite directions.

In addition, a throttling valve 64 is provided in at-least onefof the lines 61 and 62 for controlling the amount of hydraulic fluidflowing to the-ram and thereby of speed rod 28 by aset screw, or the like, and aroller 47 projects I ing laterally therefrom and riding on the edge of the co'ntour cam 46. The edge of contour cam'4'6 has a contour corresponding to the contour ofthe surface of'the workpiece to be coated. For. example, the contour cam 46 has a horizontal edge portion 46a corresponding to thecy'lin drical section of the surfaces of thegworkpie'ce 13 and an adjacent inclined section 4612 of the same; slope as the conical section of the workpiece. 1 Thus, the nozzle 18 will be raised and lowered by. contourcam 46 to follow the contour of the surface of the workpiece to .be coated as it is moved longitudinally thereof toat all .times maintain the nozzle 18; atthe same distance from thessu'rface to be I coated.

In accordance with the present invention .the rotative of movementof the carriage 2-9 mounting the nozzle 18. The throttling valve 864, 'for' simplicity of disclosure is illustrated, as an orifice platesha'ving arcuate orifices 65 which cooperate with fixed' -orifices' to reduce the area of the orifices as the plate is turned. The movable plate of the'thro'ttling valve 64 is connected to the horizontal rack 52 to change't'he speed-of movement orf' the carspeed of the workpiece 13 and the rate of advance of the nozzle '18 are correlated by the movement of the cam follower to maintain the same relative speed and a con-' stant lead of the nozzle and surface to be coated at vary-'1 ing radial distances from the rotative 'axis'to apply the and pitch.

coating uniformly in a helical pattern. As the periphery of the surface being coated at one radius is; greater than the periphery of the surface at a smaller radius, the speed of rotation of the workpiece must be. increased at the smaller radius, asindicated byicurve marked ;RPM in FIGURE 4, to produce a uni-form coating. Also, the lead or movement of the nozzle '18 longitudinally of the work- .piece 13 mustbejvariedjwith changes in'the 'rotative speed of the'workpiece as indicated by the curve marked LEAD linear an'dinversely proportional to changes in the radius -of'the-surface from the axisofrotation. Thus, the move-' 6 I 'tomaintain a constant pitch of the helicalpath of the spray pattern. Howevenbothof these' speed changes'are 1 ment of the cam follower 45'as controlled by the amour, I

cam 46 can be used as the control factor for varying both the speed of rotation of the workpiece Band, leadxof the nozzle 18 to produce a uniform coating on the surface.

' The'simplified control mechanism,iIIuStrated inFIG URE 2 is responsive tothe movement of the cam follower, 45 to vary the speed of the driving element 15 for'driving workpiece :13.

riage 29 directly with the changein rotativespeed'of the The control mechanism illustratedin FIG- URE 2 operates automatically inresponse; to the movement of the cam -follower 45 to increase the rotative speed of the workpiece 13' and the longitudinal movement of the nozzle'18 in inverse proportion todecreases in the radius of the surface of'the workpiece 13 being coated, as indicated in FIGURE 4, to relatively move the surface and nozzlei-n a helicalpath at" a constant relative speed In addition; the: nozzle'18 always will be maintained at 'the'same spaced relation to the/surface by the cam follower 45 and-depending rod 28. Thus, the nozzle 18 will delivertheatomized coating material onto the surface-of the workpiece 13 in a helical pattern andat aauniform rateiover the entire surface.

Other motor -speedchanging mechanismsmay be used in place of the variablespeed-frictiondrive illustrated in FIGURE 2 for rotating workpiece 13v and other hydraulic control mechanisms may be ,usedin' place of the flow control valved4. .Th'e'motor speed changing mechanism may comprise anelect'riccontrolifor changingthe speed of the 'motor'57, or a control for .chang-ingthe reduction gearing, or a control for changing the effective diameter of the driving pulley; Similarly, the control ofthe hydraulic ram 41 may take difi'e'rent for-ms.

FIGURE 5 illustrates an apparatus used for'coating the inside surface of rocket-motor casings iniwhich the cam follower is in the form of ,an arm projecting radially,

the workpiece 13 and the hydraulic ram 41 for advancing & the nozzle 18. The clontrol'comprises a depending rack' SO'mount ed on the cam follower 45"which meshes witha from a'sleeve 7 1 mounted on and sli'dablea-long a control shaft. 72. Sleeve 71 is'keyedt-o controlshaft 72by a key 73. to rock the control shaft from the "camfollower it). sleeve icon stitutes a' carriage, similar to 'carriage 29in FIGURE -1,' with the assemblyfof nozzle 18,

tube ll9,l n1ixin'g chamber 26, feed rolls 26, 27 and driving motor 25 mounted 'ona radial arm- 74 at one end of thesleeve 7'1. An additionaladjustable arm 75 projects spaced parallel relation to the sleeve.

from the arm 74 to permit adjustment of the height and angular position of the nozzle 18 for workpieces 13 of different sizes and shapes. The cam follower 70 engages the edge of a profile cam 46 the same as in FIGURE 1 with the edge thereof corresponding to the shape of the surface to be coated. Thus, as the sleeve 71 is moved longitudinally by the hydraulic ram 41, the cam follower 70 rocks the sleeve and nozzle 18 carried thereby to maintain the nozzle at a constant fixed distance from the surface to be coated.

The shaft 72 has crank arms 76 and 77 at one end which are connected to operate the control mechanisms for varying the speed of rotation of the workpiece 13 and the rate of lead of the nozzle 13 at rates inversely proportional to changes in the radial distance of the surface from its axis of rotation. The mechanism for changing the speed of rotation of the workpiece 13 is illustrated as a control box 78 having an adjustable arm '79 connected to the crank arm 76 on the shaft 72 by a link 80. Crank arm 77 on the shaft 72 is. connected through linkage 81 to a pressure relief valve 82 in the hydraulic system for varying the pressure of the hydraulic fluid supplied to the ram 41.

In the embodiment illustrated in FIGURE 5, the hydraulic system comprises a tank 83 for hydraulic fluid, a motor driven pump 8-4, a supply line 85 for delivering the hydraulic fluid to one end of the hydraulic ram 41. The other end of the hydraulic ram is connected by fluid return line 86 back to the tank 83 and has a flow control valve 87 therein. The flow control valve 3'7 in return line 86 may be adjusted to produce any predetermined back pressure for a desired pitch and the valve 87 cooperates with the relief valve 82 for varying the pressure of the motive fluid to control the rate of flo-w of the hydraulic fluid and speed of operation of the hydraulic ram 41 and sleeve 71. The pressure relief valve 82 supplies hydraulic fluid at a pressure proportional to the radius of the surface being coated and with a fixed back pressure moves the sleeve 71 at a rate inversely proportional to changes in the radius of the surface being coated. Thus, the speed of operation of the ram 41 is varied in accordance with changes in radius of the surface being coated and cooperates with the change speed box 78 for rotating the workpiece 13 to relatively move the surface of the workpiece and nozzle 13 in a helical path at constant relative speed and pitch. A suitable reversing mechanism also is provided in the hydraulic system for returning the nozzle 18 to a starting position.

FIGURE 6 illustrates an auxiliary apparatus used in conjunction with the apparatus illustrated in FIGURE 5 to restore the nozzle 18 to any particular position at which the coating operation has been stopped to withdraw the nozzle 18. During a flame spray coating operation, it is sometimes necessary to interrupt the cycle because of malfunction of the spray nozzle. On such occasions it is essential that after repair the nozzle be returned to the exact position along the workpiece 13 where the operation was stopped. To this end, the sleeve 71 has spaced brackets 90 and 91 mounting a rod 92 in A spool 93 is slidable on the rod 92 and adapted to engage an abutment 94. The abutment 94 may be fixed at a certain position so that the sleeve 71 moves relative to the spool 93 during an operating stroke. When the nozzle 18 is withdrawn for any reason, the spool 93 and abutment 94 are engaged so that after the nozzle is withdrawn it may be brought back to the same position by moving the sleeve 71 inwardly until the spool 93 and abutment 94 are engaged. Preferably, the abutment 94 is mounted on the rod 92 and the spool 93 mounted on a chain 95 extending around sprockets 96, one of which may be turned manually so that the operator may move the spool 93 into engagement with abutment 94. Thus the engagement of the abutment 94 with spool 93 permits the return of nozzle v18 to the exact position from where the nozzle was withdrawn or to any other position he may select. The manually operable sprocket 96 is driven by a hand wheel 97 connected by gearing to a dial 98 which indicates in inches any position of the nozzle 18 along the work piece 13.

FIGURE 7 illustrates the apparatus of FIGURE 5 applying a coating to the interior surface of a rocket engine casing 100 of a regenerative cooling type having a wall formed by a plurality of adjacent tubes 101. The rocket engine casing 100 may comprise the series of adjacent tubes 101 attached to each other in side-by-side relation, or may comprise inner and outer walls with the tubes 101 therebetween. With the form of rocket motor casing illustrated in FIGURE 7, the surface being coated may be cooled, or stated otherwise, maintained at a predetermined temperature by circulating coolant through the tubes 101. Several forms of construction having now been described in detail, the mode of operation of the apparatus is next explained.

The coating operation is necessarily dependent upon material to be coated and the coating material. If the workpiece 13 is the casing of a rocket engine and is to be coated with a refractory and erosion resistant metal oxide described and claimed in US. Patent 2,707,691, referred to above and known as Rokide, the preliminary steps will depend upon the material of the engine casing. For example, such engine casings are sometimes made of aluminum, steel or copper. It has been found that Rokide coating can be applied to an aluminum casing after cleaning and grit blasting the surface which provides a sufiiciently rough surface for good bonding of the Rokide thereto. On the other hand, the surface of stainless steel remains so smooth that it has been found necessary to interpose a metalized surface between the stainless steel and Rokide coating. It also may be desirable to initially metalize the surface to be coated to prevent oxidation. If oxidation is not completely eliminated and prevented, the Rokide coating does not properly adhere to the base metal which considerably lessens its bonding strength. Copper is another material which requires metalizing prior to application of a Rokide coating.

When an intermediate mctalizing step is required, the coating metal may be applied by the apparatus of the present invention. The coating metal in rod form is positioned between the feed rolls 26 and 27 of the motor feeding mechanism 25, see FIGURE 3, and extends through the tube 19 to the nozzle 18. Combustible gases, such as oxygen and a fuel gas are supplied to the mixing chamber 269 through the tubes 22 and 23. The gases burn at the nozzle 18 and diffuse in a spray pattern. The metal from the rod 21 to be sprayed in melted and atomized by the flame and sprayed by the blast of the gases against the surface to be coated. The workpiece 13 is rotated by its driving means and the nozzle 18 advanced by the ram 41 at varying speeds corresponding to the radius of the surface from the axis of rotation to maintain the relative speed and lead of the surface and nozzle substantially constant and the nozzle is at all times maintained at the same distance from the surface. Thus, the parts move in a helical path at a constant relative speed and pitch to produce a uniform coating on the surface. As explained above, the movement of the cam follower 47 or 76 on the profile cam 46 for maintaining the nozzle 18 at a fixed distance from the surface, also provides the control factor for varying the rotative speed of the workpiece 13 and lead of the nozzle 18 to produce a constant pitch. Thus, the apparatus of the present invention operates to uniformly coat the surface of the workpiece 13 with an intermediate metal coating. When a stainless steel casing 13 is to be met-alized, a nickel-chromium alloy is used comprising 60% nickel, 15% to 16% chromium and the remainder iron. When a casing of copper is to be metallized, pure nickel (commercial grade) may be used.

After the intermediate metalizing step, Rokide coating .at the same. constantspeed and pitch at different radial to enclose the combustible mixture of oxygen andacetyu v 7' may be applied in the same manner as' described with respect to the metal coating. When the Rokide coating is applied, the surface of the workpiece to be coated should be preheated to atemperatu-re suflicient to keep the surfacedry. In the form of the apparatus illustrated in FEGURE 1, the surface may be heatedby a hotair blast prior to coating. With the form of workpiece 10f) illustrated in FIGURE 7, hotwaterat a temperature of, for example, 140? F. is circulated through the tubes 16].. Care must be taken to maintain the heating temperature below that at which the strength of the material of the casing is affected.

A rod 21 of Rokide coating is inserted the feeding rolls 26..and 27 and through the tube 19 to the nozzle I 18. A combustible mixture supplied to the mixing cham- The flame melts and atomizes the Rokide and the blast very precise manner. Also the mounting of the spool and abutment illustrated in FIGURE 5 may be reversed. Therefore, without limitation in" this respect the inventionis defined by the following claims.

We claim: a a 1. A'pparatus'for coatingJalongitudinally extending surface concentric to an axis of revolution at varying radial distances therefrom with a flame spray of a solid material renderedmolten by the flame comprising a tube having a nozzle at one -end, means for mounting the tube and'nozzle fo'rmovement longitudinally of and toward and awayjfrom thefaxis of revolution of the surface to ber ZOfloWs through tube 19 to nozzle 18 and is ignited,

of the flame from the nozzle 18' projects a uniform flame spray of'the'rnolten coatingin a fixed pattern from the 1 I nozzle 18 as the Work-piece 13 rotatesa'nd the nozzle 18 advances along thesurface, As explained above,*the

nozzle 18 is maintained at a fixed distance from the surface to be coated by the cam follower 47 or 70 as controlled by the profile cam 46; In addition, the move ment of the cam follower 47 or 70 controls thevariable speed drives for rotating the workpiece 13 Jand the 'hybe coated, means for supplying a combustible mixture to the tube whichburns at theoutlet from nozzle, means for ceding coating material through the tube to the nozzle which isfmeltedib'y the flame and propelled in a fine spray in a diverging pattern by theblast of the flame, a

variable speed motor connected to rotate the surface to be coatedat an'angular: velocity inversely proportional 'tochanges in the radius, of said surface from its axis of revolution to relativelymove the nozzle and surface at a constant linear velocity vtherebetvveen, a variable speed motor connected; to move the nozzle'lo'ngitudinally of the surface to .bec-oated at a velocity inverselyproportionalto changesin theradius of said surface to maintain a constant pitch between turns of the helical path traced draulic ram 41' for advancing the nozzle 18, to maintain the relative speed and lead of thesurface and nozzle' constant. The coating'oper-ation is continued with the coating material being sprayed ontothesurface ofrthe workpiece 1-3 in a helical lpath of constant pitch to produce a uniform layer of the coating material throughout; the length of the workpiece. a a

If for any reason the coating operationisstopped,,the

position of the spool '93 on the rod 92,; see FIGURE 6; will in dicatethe position. After the nozzle .18 has been withdrawn and the malfunction remedied, thejnozzle 18'v is moved back to the position where the abutment 94 engages the spool 93 and the coating operation aga-ininitiated. To this end the "abutment 94 may be initially ad ijusted along rod 92 for any particular workpiece and the ing uniformly on, a surf-ace of varying radial-distances, about an axis of revolution. It also will beobserved that the present invention provides an apparatus for producing a flame spray ofa normally solid materialwhile the H parts are moved relative to each other in a'helical path positions. 'It also be observed 'that thelpresent invention provides anjapparatns forrelatively moving a flame spray nozzle andsurface to be coated so as to cause -:bythe nozzle on the surface, a profile cam'having a contour corresponding to the surface tobe coated, and a cam follower engaging the profilecam and connected to the nozzle and variable speed motors for maintaining the nozzle ata constant distance from the surface to be coated as it moves'longi-tudinally thereof and maintaining a constant relative velocity and pitch of the nozzle and surface at all radial distances ofrevolution. l a 1 V a I v 2. Apparatusfor coating the longitudinally extending surface of a body which isconcentric to an axis of revolution at varying distances along the body Witha flame spray of the surface from the axis 'of asolid coating material comprising, means for mounting the body for rotation about the axis of revolution, a control shaft extending parallel to the axis of revolution of the body at one 'sidethereof, asleeve slidable longitudinally along the control shaft, a radial arm projecting 'Jfrom the sleeve, a mixing tube mounted on said radial arm vides anapparatus' for applying :a molten atomized coatthe nozzleto follow the irregular contour of the surface at the same distance therefrom. ltwillybe still further j observed that thepresent invention provides an apparatus which is of .relativelyjsimple and compact. construction; and one-Which is reliable inoperation to apply a uniform coating on the surface of aworkpiece.

.While several modifiedconstructions are be made in the construction andarrangements of elemerits withoutvdeparting from thespirit' or scope of the invention. For example, it has been-foundadvantageous lene or other gas in an envelope of air also ejected from the nozzle. Theenve'lope or curtainof air, contains the flame cone and, by using suitable deflectors, variousangles andhaving a nozzle at its endwhich overlies'the surface to be coated, means for supplying a combustible. mixture to the tube which burns .at the .outlet' from the nozzle, means for feeding a strip, of the solid coating material I through the mixingjtube and nozzle which is melted by the flame and propelled in a fine spray'in a diverging pattern by theblast of the. flame, variable speed driving means for rotating the bodyfrelative to the nozzle, variable speed driving means connected to move thesleeve along the" control shaftto apply the coating material on the surface in a spiral path, a contour cam having the'contour of the surface to be coated, a radial arm projecting from the sleeve and having a carn'followerengaging'the contour cam for rocking the sleeve as it moves longitudinally along the c'ontrolshaftto maintain'the nozzle at a fixed distance from the surface, and linkage operated by the rocking of the'sleeve to adjust the speed of the respective driving means whereby torotate the surface to be coated illustrated a d) a described, it will be understood that further changes may 6 and move thelsleeve along the rotating surfaceat speeds inversely proportional to the distance of the surface. from the axisfo'fgrevolut-ion to apply the coating material at a substantially constant rate to the surface. 7 j 3. Apparatus 1in accordance with claim 2 in which the driv-in g' means for movingthe sleeve is aghydraulic ram, 'a hydraulic system for supplying fluid to the ramcompris- "ingl-i'nes to and from the ram and a pump connected to 1 ,lthe lines, a valve in one of the lines for controlling the of the flame issuingfrorn the nozzle can beachieved,

Such control of the flame,in turn, controls the deposition'of coating material on the surface being coated inf a ,fl-ow ojf'hydraulic' fluid and the rate of movement of the sleeve, and means actuated by the contour cam for operating the valve tom-ovethe sleeve; ata rate inversely'proporaieacoi tional to the distance of the surface from the axis of rotation.

4. Apparatus in accordance with claim 3 in which the hydraulic system comprises a tank, one of the lines connecting the pump to one end of the hydraulic ram,

' another line connecting the other end of the hydraulic ram to the tank, the valve in one of the lines comprising a variable pressure relief valve in the line from the pump to the ram to control the pressure of the hydraulic fluid supplied to the ram.

5. Apparatus in accordance with claim 2 in which the sleeve mounts a rod in spaced parallel relation thereto, a spool on the rod, an abutment, and said abutment and spool being relatively movable along the rod to indicate a particular position of the sleeve whereby to adapt the nozzle to be returned to the exact location where a coating operation is stopped by moving the spool and abuting movement along the rod, the abutment is fixed to the 1% rod, means for manually operating the conveyor to move the spool into engagement with the abutment, and an indicator cooperating with the conveyor to indicate the position of the abutment relative to the surface to be coated.

References (fitted by the Examiner UNITED STATES PATENTS 2,316,959 4/43 Hinkley et al. 118321 2,345,834 4/44 Schweitzer 11832l 2,598,246 5/52 Fowler 118-321 2,707,691 5/55 Whfiiildon ll7-105.2 2,726,617 12/55 Knapp 118-47 XR 2,977,928 4/61 Knutsen et a1 l18321 FOREIGN PATENTS 718,190 11/54 Great Britain.

RICHARD D. NEVIUS, Primary Examiner.

JOSEPH B. SPENCER, Examiner. 

1. APPARATUS FOR COATING A LONGITUDINALLY EXTENDING SURFACE CONCENTRIC TO AN AXIS OF REVOLUTION AT VARYING RADIAL DISTANCES THEREFROM WITH A FLAME SPRAY OF A SOLID MATERIAL RENDERED MOLTEN WITH BY THE FLAME COMPRISING A TUBE HAVING A NOZZLE AT ONE END, MEANS FOR MOUNTING THE TUBE AND NOZZLE FOR MOVEMENT LONGITUDINALLY OF AND TOWARD AND AWAY FROM THE AXIS OF REVOLUTION OF THE SURFACE TO BE COATED, MEANS FOR SUPPLYING A COMBUSTIBLE MIXTURE TO THE TUBE WHICH BURNS AT THE OUTLET FROM NOZZLE, MEANS FOR FEEDING COATING MATERIAL THROUGH THE TUBE TO THE NOZZLE WHICH IS MELTED BY THE FLAME AND PROPELLED IN A FINE SPRAY IN A DIVERGING PATTERN BY THE BLAST OF THE FLAME, A VARIABLE SPEED MOTOR CONNECTED TO ROTATE THE SURFACE TO BE COATED AT AN ANGULAR VELOCITY INVERSELY PROPORTIONAL TO CHANGES IN THE RADIUS OF SAID SURFACE FROM ITS AXIS OF REVOLUTION TO RELATIVELY MOVE THE NOZZLE AND SURFACE AT A CONSTANT LINEAR VELOCITY THEREBETWEEN, A VARIABLE SPEED MOTOR CONNECTED TO MOVE THE NOZZLE LONGITUDINALLY OF THE SURFACE TO BE COATED AT A VELOCITY INVERSELY PROPORTIONAL TO CHANGES IN THE RADIUS OF SAID SURFACE TO MAINTAIN A CONSTANT PITCH BETWEEN TURNS OF THE HELICAL PATH TRACED BY THE NOZZLE ON THE SURFACE, A PROFILE CAM HAVING A CONTOUR CORRESPONDING TO THE SURFACE TO BE COATED, AND A CAM FOLLOWER ENGAGING THE PROFILE CAM AND CONNECTED TO THE NOZZLE AND VARIABLE SPEED MOTORS FOR MAINTAINING THE NOZZLE AT A CONSTANT DISTANCE FROM THE SURFACE TO BE COATED AS IT MOVES LONGITUDINALLY THEREOF AND MAINTAINING A CONSTANT RELATIVE VELOCITY AND PITCH OF THE NOZZLE AND SURFACE AT ALL RADIAL DISTANCES OF THE SURFACE FROM THE AXIS OF REVOLUTION. 